The present invention relates to heat engines and more particularly, to a novel engine in which the combustion chamber is separated from the expander which receives hot gases from the combustion chamber.
The engines of the invention are thermodynamically similar to the gas turbine, and can utilize one or more pistons or other displacement devices for compression and expansion. Combustion is external of the displacement devices, thereby providing many advantages. The use of a combustion chamber separated from the displacement devices provides greater flexibility as to fuels used. Thus, solid, liquid or gaseous fuel may be utilized. The combustion temperature may be lower and the combustion time longer, resulting in more complete combustion, to thereby substantially reduce the level of pollutants in the exhaust. In addition, no critical ignition timing is necessary in such an arrangement.
One or more devices, or a portion of the operating cycle of the device, is utilized to compress air which is passed through a heat exchanger to be preheated while cooling exhaust gases and which is then introduced into the combustion chamber. Excess compressed air may be stored in an accumulator for subsequent use when necessary, for example, during periods of peak power demand or when the engine is cold.
During braking, regenerative braking may be achieved whereby the engine is slowed while compressing air in the compressor which is passed to an accumulator for storage and subsequent use when needed. The compressor may be disconnected on start-up so that there is very low starting load. The stored compressed air is also available for powering auxiliary equipment as well as for meeting peak power demands and for engine start-up. The availability of compressed air for start-up provides easy cold weather starting and if desired enables the fuel to be cut off completely on idle since the engine can be restarted immediately on demand in view of the availability of compressed air which can be passed through the system to the expanders.
The engines of the invention may in appropriate sizes be employed in a wide variety of applications. For example, when employed to power an automobile, the engines of the invention would have increased efficiency, reduced exhaust levels of pollutants and heat, fast starting capability, compressed air availability, dynamic braking, and instant power availability. For buses and trucks, the saving of braking energy would be a particularly significant factor. The engines of the invention would also find application in locomotives, stationary power plants, marine engines and airplanes. A primary advantage of use in aviation would be high horsepower availability for the size of the engine during take-off because of the availability of the stored compressed air for use as a take-off assist.
Another advantage of the invention resides in its great versatility, engines can be made with virtually any number (even or odd) of cylinders, and a wide range of compressor/expander ratios (from 1:1.5 to 1:10 or about 5) can be used. The invention can also be embodied in a turbine form.
The above and other objects, features and advantages of the invention will become more apparent as this description proceeds.